The primary objective of this research is to provide data that can be used to evaluate the safety of present and future ultrasound ophthalmic systems employed in diagnosis. Toward this goal determinations will be made of those ultrasonic radiation dosages needed to produce damage to ocular and orbital tissues of irradiated rabbits. The safety of these dosages will be evaluated on the basis of a comprehensive program of tissue analysis. Accurate determination of the applied radiation levels will be accomplished by experimental and analytic techniques and determinations of the acoustic properties of ocular and orbital tissues. The knowldge gained from this research will provide a foundation for the formulation of ultrasonic safety standards applicable to the design of ultrasonic equipment and the planning of clinical procedures.